Three primary color video signals produced by three television cameras are standard television signals and are the so-called interlaced signals. When such those three primary color video signals are produced in the HDTV system each of them has 1125 number of scanning lines per frame and a transmission bandwidth of the luminance signal thereof extending over 20 MHz which is about four times as much as that of the NTSC system being 4.5 MHz. It is therefore necessary to perform bandwidth compression in order to transmit such HDTV signals through conventional TV transmission lines. One of systems for achieving this is known as the so-called MUSE (Multiple Sub-Nyquist Sampling Encoding) system.
On the other hand, for recording and reproducing HDTV video signals using a recording medium, the bandwidth compression or data compression is required also for utilizing existing recording apparatus. The present assignee has proposed an HDTV signal recording/reproducing system in Japanese Patent Application No. 2-169841.
A recording/reproducing system of this earlier application, as shown in FIG. 1(a), converts interlaced HDTV signals each having 1125 scanning lines, a number of horizontal pixels equal to N (N is an integer, for example, N=960), and a field frequency at 60 Hz into sequential (non-interlaced) scanning video signals each having 525 scanning lines, a number of horizontal pixels equal to N/2, and a frame frequency at 60 Hz for recording. Then, as shown in FIG. 1(b), the thus recorded signal is reproduced as sequential scanning video signals having 525 scanning lines, the number of horizontal pixels being N dots, the frame frequency at 60 Hz, and an aspect ratio equal to 16:9. In this manner, a current NTSC recording apparatus and a medium can be utilized to record/reproduce video signals with high image quality.
It should be noted that when a movie film is used as a video source, the number of horizontal pixels may be increased to 2N dots/line (N=960) since the resolution of the film is sufficiently high.